A070236 - cp's OEIS frontend

A070236 a(n) = Sum_{k=1..n} (core(k) - phi(k)), where core(k) is the squarefree part of k.

n	a(n)
1	0
2	1
3	2
4	1
5	2
6	6
7	7
8	5
9	0
10	6
11	7
12	6
13	7
14	15
15	22
16	15
17	16
18	12
19	13
20	10
21	19
22	31
23	32
24	30
25	11
26	25
27	10
28	5
29	6
30	28
31	29
32	15
33	28
34	46
35	57
36	46
37	47
38	67
39	82
40	76
41	77
42	107
43	108
44	99
45	80
46	104
47	105
48	92
49	51
50	33
51	52
52	41
53	42
54	30
55	45
56	35
57	56
58	86
59	87
60	86
61	87
62	119
63	90
64	59
65	76
66	122
67	123
68	108
69	133
70	179
71	180

[0, 1, 2, 1, 2, 6, 7, 5, 0, 6, 7, 6, 7, 15, 22, 15, 16, 12, 13, 10, 19, 31, 32, 30, 11, 25, 10, 5, 6, 28, 29, 15, 28, 46, 57, 46, 47, 67, 82, 76, 77, 107, 108, 99, 80, 104, 105, 92, 51, 33, 52, 41, 42, 30, 45, 35, 56, 86, 87, 86, 87, 119, 90, 59, 76, 122, 123, 108, 133, 179, 180]

cp's OEIS Frontend

A070236 a(n) = Sum_{k=1..n} (core(k) - phi(k)), where core(k) is the squarefree part of k.

Table of values

List of values

n	a(n)
1	0
2	1
3	2
4	1
5	2
6	6
7	7
8	5
9	0
10	6
11	7
12	6
13	7
14	15
15	22
16	15
17	16
18	12
19	13
20	10
21	19
22	31
23	32
24	30
25	11
26	25
27	10
28	5
29	6
30	28
31	29
32	15
33	28
34	46
35	57
36	46
37	47
38	67
39	82
40	76
41	77
42	107
43	108
44	99
45	80
46	104
47	105
48	92
49	51
50	33
51	52
52	41
53	42
54	30
55	45
56	35
57	56
58	86
59	87
60	86
61	87
62	119
63	90
64	59
65	76
66	122
67	123
68	108
69	133
70	179
71	180

n	a(n)
1	0
2	1
3	2
4	1
5	2
6	6
7	7
8	5
9	0
10	6
11	7
12	6
13	7
14	15
15	22
16	15
17	16
18	12
19	13
20	10
21	19
22	31
23	32
24	30
25	11
26	25
27	10
28	5
29	6
30	28
31	29
32	15
33	28
34	46
35	57
36	46
37	47
38	67
39	82
40	76
41	77
42	107
43	108
44	99
45	80
46	104
47	105
48	92
49	51
50	33
51	52
52	41
53	42
54	30
55	45
56	35
57	56
58	86
59	87
60	86
61	87
62	119
63	90
64	59
65	76
66	122
67	123
68	108
69	133
70	179
71	180

n	a(n)
1	0
2	1
3	2
4	1
5	2
6	6
7	7
8	5
9	0
10	6
11	7
12	6
13	7
14	15
15	22
16	15
17	16
18	12
19	13
20	10
21	19
22	31
23	32
24	30
25	11
26	25
27	10
28	5
29	6
30	28
31	29
32	15
33	28
34	46
35	57
36	46
37	47
38	67
39	82
40	76
41	77
42	107
43	108
44	99
45	80
46	104
47	105
48	92
49	51
50	33
51	52
52	41
53	42
54	30
55	45
56	35
57	56
58	86
59	87
60	86
61	87
62	119
63	90
64	59
65	76
66	122
67	123
68	108
69	133
70	179
71	180